1. Field of the Invention
The invention relates generally to marine propulsion devices such as outboard motors and stern drive units. More particularly, the invention relates to transmissions including reversing transmissions for such marine propulsion devices, and is applicable to both so called "counter rotation" and to so called "standard rotation" transmissions. The invention also relates to methods of assembling a reversing transmission in a marine propulsion device.
2. Reference to Prior Art
In the past, some so called "counter rotation" transmissions have included two-piece propeller shafts, i.e., propeller shafts including a forward portion and a rearward portion. Transmission of forward thrust to the gearcase was provided by a thrust ring on a rearward part of the propeller shaft. Inclusion of the thrust ring on the propeller shaft prevented positive assembly of a shift actuating mechanism at the front of the propeller shaft. As a consequence, counter-rotation transmissions employed split shafts to accommodate positive connection of the shift actuating mechanism at the front of the forward propeller shaft portion before assembly of the rearward propeller shaft portion (including the thrust ring) with the forward propeller shaft portion. Standard rotation propeller shafts were one-piece shafts.
More specifically, in the past, and in both counter rotation and standard rotation arrangements, the shift actuating mechanism included provision, at the forward end of the propeller shaft, of a shift shaft having an annular groove and provision of a bell crank shift lever including a leg with an outer end which entered into the groove.
In both the prior counter rotation and standard rotation arrangements, the bell crank shift lever was pivotally mounted in a shift housing and the forwardly locating bevel gear was also initially assembled in the shift housing. Thereafter the resulting shift housing assembly was fitted in the forward end of the gearcase cavity and prevented from rotating by interengagement of a pin on the shift housing with a slot in the gearcase. In addition, and prior to insertion of the shift housing assembly in the gear cavity, the shift shaft and a clutch dog were assembled on the propeller shaft (or the forward portion thereof in the case of the counter rotation arrangement) to form a propeller shaft assembly which was thereafter inserted through the forwardly located bevel gear, and the shift shaft was operably engaged with the pivotally mounted shift lever. The shift housing assembly with the preassembled shift lever and forwardly located bevel gear, together with the propeller shaft assembly (with the shift shaft and shift lever operably engaged) were then inserted into the gearcase cavity.
In the past, the next step was to fix a drive pinion on the drive shaft and in meshing engagement with the forwardly located bevel gear. Due to the crowded condition within the gearcase cavity, i.e., the fact that the propeller shaft was already located in the cavity, proper "torquing" of the nut retaining the drive pinion on the drive shaft was a difficult and costly operation.
Thereafter, in the standard rotation arrangement, a rearwardly located bevel gear and a propeller shaft bearing retainer were then installed into the gearcase cavity in surrounding relation to the propeller shaft. The bearing retainer was then fixed in place.
In the counter rotation arrangement, the rearwardly located bevel gear (together with an assembled thrust canister) was assembled on the rearward propeller shaft portion forwardly of a thrust ring on the rearward propeller shaft portion. This preassembly also included a propeller shaft bearing retainer which was attached to the thrust canister and extended therefrom rearwardly of the thrust ring. The resulting preassembly was then installed into the gearcase cavity, with the rearward propeller shaft portion engaged with the forward propeller shaft portion for common rotation, with the rearwardly located bevel gear in meshing engagement with the drive pinion and in bearing engagement with the gearcase, with the thrust canister engaged with the gearcase for forward thrust transmission therebetween, and with the propeller shaft bearing retainer in engagement with the gearcase cavity. Thereafter the bearing retainer was fixed in place to retain the components within the gearcase cavity.
Attention is directed to the following U.S. Pat. Nos.:
BLANCHARD, 4,302,196, Nov. 24, 1981 PA1 TAGUCHI, 4,637,802, Jan. 20, 1987 PA1 HARAOA, 4,689,027, Aug. 25, 1987 PA1 HIGBY, 4,850,910, Jul. 25, 1989 PA1 McELROY, 4,861,295, Aug. 29, 1989 PA1 HIGBY, 4,865,570, Sep. 12, 1989
Attention is also directed to the 1987 Johnson/Evinrude Service Manual. The counter rotation arrangement disclosed therein was provided by operating the counter rotation engine in the opposite rotary direction from the direction of rotation of the standard rotation arrangement.